Thread-cutting mechanism for sewing machines



April 22, 1924.

. P. HLEB THREAD CUTTING MECHANISM FOR SEWING MACHIN Filed July 1, 1920 2 Sheets-Sheet 1 INVEYNTUR flaw/1 M ATTORNEY April 22, 1924; 1,491,010

P. HLEB THREAD CUTTING MECHANISM FOR SEWING MACHINES Filed July 1. 1 9 2c 2 Sheets-Sheet 2 INVENTOR QRNEY Patented Apr. 22, 1924.

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PETER HLEB, 013 ELIZABETH, NE'W JERSEY. ASSIGNOR TO TI-IE SINGER MANUFACTUlEt- ING CO'IVIPANY, OF ELIZABETH, NEXV JERSEY, A CORPORATION OF NEW JERSEY.

THREAD-UUTTING INLECHANISM FOR $EWING JK'IACHINES.

Application filed July 1, 1920.

To (/71 whom it may concern:

Be it known that I, Pn'rna T'TLEB, a citizen of the United States, residing at Elizabeth, in the county of Union and State of New Jersey, have invented certain new and use fnl Improvements in 'llhread-Cutting MechflDlSillS for Sewing lvlachines of which the following is a specification, reference being had therein to the accompanying drawings.

'hollow work-arm 2 spaced above the base This invention relates to a tlrreadnipper and cutter and particularly to such a nipper and cutter as employed in connection with a rotary hook in a cylinder arm barring and tacking or button-sewing machine.

An object of the invention is to provide a simple and easily assembled arrangement of the tln'ead-detaining and severing means on the throat-plate and one that will require very little space transverse the work-arm so that it may be applied to narrow work-arms and still may be so located with respect to the loop-taker as not to interfere with the removal and insertion of the lower thread mass.

In the preferred en'ibodiment of the invention the thread-detaining and severing means is mounted on a support pivoted so that it may be oscillated on the under side of the throat-plate. This throat-plate forms the entire upper surface of the free outer end of the hollow work-arm and also carries an operating lever fulcrumed thereon intermediate its ends outwardly of the pivot for the thread-detaining and severing means. One end of the lever has a link connection with the pivoted support while the other end has detachable link connection with a bar extending through and longitudinally of the hollow arm to the stop-motion mechanism for the machine.

All the parts when assembled are within the confines of the work-arm and the whole thread-detaining and severing means may be detached from the work-arm with the throat-plate after the detachable link connection between the bar and the lever is disconnected. This allows ready removal of the tln'ead detaining and severing means for inspection, adjustment and repair, and also allows assembling thereof on the throat-plate before it is applied to the work-arm.

Referring to the accompanying drawings illustrating the preferredembodiment of my invention. Fig. 1. is a rear side elevation of the machine. l 2 is a bottom plan view.

Serial No. 393,351.

Fig. 3 is a bottom plan view on an enlarged scale of the throat-plate removed with my thread-severing and detaining means assem-- bledthereon. Fig. 4: is a detail perspective view, of the ledger-blade;and Fig. 5 is a detail, perspective view of the bobbin-thread pull-off and shear-blade.

The machine frame comprises a standard 1 provided with a horizontally extending thereof. The frame also has an overhanging bracket-arm 3 in the head 4 of which the needle-bar 5 carrying the needle 6 is mounted to reciprocate in a well known manner. llithin the arm 3 is mounted the main driving shaft 7 provided at the rear end with loose and tight pulleys 8 and 9, respectively. the tight pulley 9 being provided with a stopping cam having a stop-lug 10. Upon the shaft "7 within the arm 3 is a bevel-gear 11 meshing with a gear 12 upon a vertical shaft 13 provided at its lower end with a second bevel-gear 14 meshing with a bevelgear 15 on the loop-taker shaft 16 extending through the hollow work-arm to the rotary hook 17 which is fixedly mounted on the shaft 16. The gears 11, 12, 1 1 and 15 are so proportioned as to give a two-to-one rotation to the loop-taker shaft, the shaft 16 having two revolutions to one of the shaft 7.

The standard 1 is provided with a trans.- versely extending shaft 18 on which is mounted the cam-disk 19. This disk is operated from the main-shaft 7 by means of a worm 20 meshing with a wornii-wheel 21 on the shaft 1.8. From the cam-disk 19 various movements are imparted to the work-holder, stop mechanism and the thread-cutter as will presently be described.

Mounted for jogging and reciprocating movement upon the hollow work-arm .a work-support 22 and button-clamp 23 both secured to the block 24. The wor t-support and button-clamp are given movements transverse the work-arm by means of the bellcrank 25 fulcrumed on the base at 26, connected to the lower end of the lever 27 by means of a link 28, the lever 27 being ful crumed at 29 in a bracket 30 secured to the frame of the machine. The lever 27 is rocked through a cam-follower 8-1 upon the upper end thereof which works in a suitably shaped cam-groove 32in the cam-disk19. Movements longitudinally of the work-arm are imparted to the work-support 22 and the button-clamp 23 by means of a second lever and suitable cam (not shown) mounted on the opposite side of the bracket-arm 3. The work-support, button-clamp and the means for imparting jogging movements, thereto are substantially those disclosed in the patents to Sullivan No. 777,56l, of December 18, 190st and Barron No. 1,098,2 l1 of April lat, 1914.

A stop-lever 33 is pivoted in the frame at and is provided at its upper end with a belt-shitt Also mounted in the upper end of this lever is a spring-pressed, plunger 36 adapted to cooperate with the stopping cam and the .stoplug 10 thereon. The stop-lever 2523 also has a limited sidewise or overthrow movement on the frame because of a pivot connection at 37. Connected to the lower end of the stop-lever is a spring secured at the opposite end to a pin 39 on the base of the machine, said spring tending to pull the stop-lever into stopping position as shown in Fig. 1.. Mounted upon the frame and adapted to be release-d by means of a lug, not shown, on the rear of the cam-disk 19 is a spring-pressed latch 40 which retains the stop-lever in inoperative position holding the driving belt on the tight pulley 9.

The thread-detaining and cutting mechanism is mounted upon the under side of the throat-plate ll which, in the embodiment shown, is substantially the same width as the top of the work-arm 2 and forms the outer upper surface thereof. Secured to the under side of this throat-plate is a doivnwardly extending supporting bracket 42 and pivotally supported between the free end. l3 er this bracket and the throat'plate is a supporting arm lat upon which is mounted the hread-cutting and holding means. A needle-loop detaining and bobbin-thread pulloii blade 1-5, together with a lint yielding bobbin-throad-nipper-blade l0 is secured to the supporting arm ll by meansv of a screw 47. Also secured to the su n'iorting arm ll is a flat barbed. plate l8. The needle-loop detaining and bobbin-thread pulloff blade to is pronded with an np\ -.i-nrdly extending inclined shear blade 49, as shown in Fig. 5, said shear-blade eoi'iperating" with a ledgerblade 50 secured to the underside of the throat-plate by means of a screw 51. The

ledger-blade has a limited adjustment upon.

the throat-plate because of the elongated opening 52 therein through which the screw 5]. extends. The free end of the needle-loop detaining and bobbin-thread pull-oil, blade has frictional engagement when operated with the surface of a spring-plate 53 which prevents thedetained needle-loop from falling oil- Fulcrumed intermediate its ends at 54 to the throatplate on the opposite side of the pivot "for the supporting arm 4-4 from the needle and the loop-taker is a lever 5-l having connection at one end by means of a link 55 with the supporting arm ll at point 56. The opposite end 57 of said lever has link connection 58 with the drmv-bar 59, said draw-bar being mounted so as to reciprocate within a groove (30 formed in a wall or the hollow work-arm 2 but does not project beyond the outer surface thereof the bar being retained in said groove by means of a. plate secured to the wall of the work-arm in any desirable manner prefer ably by screws as shown in Fig. 1. The under side of the throatplate il is provided with a recess (51 into which the free end oi? the shear-blade 49 extends.

The draw-bar 59 is connected at its rear end with a block 62 provided with a recess 63 into which extends the lower end (ll of the lever l ulcrumed at 66 in a. bracket 67' secured to the machine frame, the upper end of the lever being provided with a camfollower fitting in a cam-groove 68 in the cam-disk it). The block (52 is also provided with a roller-stud 69 embraced by the forked end of a bellcrank-lever 7O fulcrumed at 71 to the machine. On the other arm of the bel-lcrank is a springpressed plunger '72 urged to its outer position by the spring 73. The lower end of the stop-lever 33 is pro vided with a recess into which the plunger 72- is forced by the spring '73 when the bell crankdever 70 is moved to bring said plunger in al'inement with said recess.

Pivotally mounted by means of the bracket 'F-l on the base of the frame is a lever 75 which may be connected to any suitable treadle mechanism, not shown. The lever 75 is adapted to reciprocate a. plungerrod 76 against the action of a spring 77, the end oil the plunger-rod 78 being adapted to abut against the lower end of the stop-lever to force this lever into running position. The stop mechanism and the means for operating the cutting and nipping mechanism therefrom are substantially those disclosed in the patent to Barron, No. 1,093,2-l1. before ,mentioned. I

The loop-talnar l7, as iliselosed. is or the rotary hook type and rotated constantly in the same direction. It is a peculiarity of this type of loop-taker that itdoes not pass bodily through the needle-loop but carries the loop around the lower thread niass,,giving the needle-loop a halt twist in such carriage so that the work-limb oi the needleloop is closely adjacent the lower thread immediately under the work and therefore both the lower thread and the work-limb of the needle-loop are separated from the supply limb of the needle-loop and may be seized and severed simultaneously by a single shear cut of the shear-blade 49 upon op eration of the thread-cutter at the proper time. In the present arrangement, of the device the bobbin case position fingerlit) brackeet 79 is secured to the vertical end wall of the hollow work-arm 2 by means of the screw 80.

After the loop-taker and its operating mechanism is assembled within the workarm the lower open side of this arm is closed by means of a" curved cover 81 which is provided'with oppositely extending ribs 82 slidable in grooves formed in thework-arm so that said cover 81 may be readily slid into place or removed to expose the mechanism. The tl'iread-detaining and cutting means is enclosed by means of a cap 83 hinged at the point 84 to the cover 81.

' It will be noted that none of the elements of the thread-nipper and cutter or its operating mechanism extend beyond the walls of the hollow work-arm but occupy very little space transverse of this arm. It is therefore unnecessary to widen the arm to accommodate this thread-nipper and cutter with its cutting mechanism, thus allowing the use of a very narrow work-arm. If it is desired to have a fiat bed machine a cloth-plate 85 may be secured thereto, in the embodiment shown, by means of blocks 86, 87, adapted to extend into short recesses 88. 89, cut into the outer surface of the work-arm.

In operation at the'beginning of a stitching cycle the bell crank-lever 75 is depressed by means of the foot-treadle and through the slidable rod 76 the lower end of the sto ylever 33 is forced outwardly shifting the belt from the loose pulley 8 to the tight pulley 9 and removing the plunger 36 from alinement with thestop-lug 10. Upon the first reciprocation of the needle 6 the loose end of needle-thread is drawn through the work to the under side of the throat'plate by the rotating hook 17. At this time the cam-follower on the upper end of lever 65 rides off the raised portion 68 onto the dwell 6S, slightly retracting the nipper 48 and also the nipper 46 and the needle-loop detaining and bobbin-thread pull-ofi' blade 45. The retraction of the barbed portion of the nipper 48 across the needle-opening shown at all in Fig. 3, detains the free end of the needle-thread against the under side of the throat-plate, the bobbin-thread being held by the nipper 4L6. At the end of the forth stitch the cam-follower on lever 65 moves into the long dwell 68", further retracting the nipper and releasing the bobbinthread and also the needle-thread, suflicient stitching having been made to prevent unravelling.

The stitching then proceeds in the usual manner and at the end of the stitching operation the needle makes several stitches in the same hole to act as tying stitches. As the needle goes down on the last reciprocation the catch is released by a lug, not shown, on the surface of the cam-disk 19,

main-shaft continues to turn due to its momentum, the needle rises and as its loop is cast off the thread-cutter advances and the loop-detainer pulls off the bobbinthread and enters the loop. The advance of the thread-cutter and detainer is caused by the follower on the lever riding up on the raised portion 68 of the cam-groove 68. The bellcrank-lever 70, being also connected to the lever 65, is shifted, bringing the plunger 72 into alinement with the recess in the lower end of the stop lever 33 just before the stop-lug 10 comes in contact with the plunger 36. Then as the lever 33 is given its sidewise or overthrow movement by the momentum of the shaft the bellcrank is oscillated, and through the roller-stud 69 and draw-bar 59 the thread-cutter and detainer means is given its final movement, nipping the bobbin-thread beneath the spring-plate l6 and severing this bobbinvthe machine all that is necessary is to disconnect the detachable connection at 58 and remove the throat-plate. This allows easy access to the thread-detaining and severing device for inspection, adjustment and repair, and also allows complete assemblage thereof on the throat-plate before insertion in the machine. If it'is desired'to use the machine without the throat-detaining and severing means, all that is necessary is to remove the throat-plate with this mechanism assembled thereon and insert in place thereof a throat-plate without this mechanism.

Although the device is illustrated and described as employed with a. rotary hook, it is clear that it is not confined to use with this type of loop-taker in all aspects of the invention but in certain aspects may be used with any other type of loop-taker desired.

Having thus set forth the nature of the invention, what I claim herein is 1. In a sewing machine having stitchforming mechanism, a removable throatplate, a thread-detaining and severing means movably mounted on the under side of the throat plate, a lever fulcrumed on said. throat-plate, a link connection from said lever to the thread-detaining and severing means, operating means, and a detachable link connection bet-ween said lever and the operating means.

2. In a sewing machine, in combination, stitch-forming mechanism and stop mechanism therefor, a frame including a workarm, a removable throat-plate mounted thereon, a thread-severing and detaining means movably mounted on the under side of the throat-plate, a lever fulcrumed on the throat-plate and having link connection with said thread-severing and detaining means to operate the same, and a detachable link connection between said lever and the stop mechanism.

3, A sewing machine having a frame including a hollow work-arm free of support at one end and at its other end joining the main frame of the machine above the base ofthe latter so as to afford free space under said arm, stitch-forming mechanism incorporated in said frame, tlnead-severing means movably mounted to cut the thread on the under side of the work, means for operating said thread-severing means comprising a lever fulorumed intermediate its ends at the free end of the work-arm, a link pivotally connected at one end to said lever and at its opposite end to said thread-severing means, operating means, and a second link pivotally connected at its opposite ends, respectively, to said lever and said operating means.

4-. In a sewing machine, in combination, a frame having a hollow work-arm extending therefrom, stitclnforming mechanism including a reciprocating needle and a looptaker cooperating therewith, a detachable throat-plate, a tln'ead-detaining and severing means movably mounted on the under side of the throat-plate, a lever fulcrumed int rmediate its ends on the throat-plate and having link connection at one end to said tln'eactdetaining and severing means, a stop 'n'iotion mechanism for the stitching mechanism, and a link connection from the other end of the lever to the stop-motion mechanism.

5. In a sewing machine, in combination, a frame having a hollow work-arm extending therefrom, stitch-forming mechanism in cluding a reciprocating needle and a looptaker cooperating therewith, stoprmotion mechanism for the stitch-forming mechanism, a detachable throat-plate adjacent the free end of the Work-arm, a thread-detaining and severing means pivotally mounted on the under side of the throat-plate, a lever fulcrumed on said throat-plate having a link connection for operating the thread-detaining and severing means, a second link cornected to said lever, said thread-detaining and severing means, lever and. links all confined Within the outer walls of the hollow work-arm and an operating means within said arm having connection with the stop motion mechanism and detachably connected with said second link.

(3. In a sewing machine for separate stitching operations, in combination, a frame provided with a hollow work-arm extending horizontally therefrom, stitch-forming mecha nism comprising a reciprocating needle and a lower-thread loop-taker mounted to rotate continuously in the same direction within the hollow work-arn'i and adapted to cooperate with the needle to form stitches, a throat-plate, a thread-severing and detaining means mounted to operate on the under side of the throat-plate and adapted to cut the lower thread and the work-lin'ib of the needleloop simultaneously at the end of a stitching operation, a lever pivoted to the under side of the throat-plate and adapted to operate the thread-detaining and severing means, a link pivoted to the lever, a stop motion mechanism for the stitch-forming mechanism, and a bar located within the periphery of the workarm connected to said. link and to said stop-mechanism whereby the thread-detaining and severing means is operated by said stop mechanism.

in testimony whereof, I have signed. my name to this specification.

PETER HLEB. 

